This invention relates to a novel method of preparing a group of polyfluoroenolates from polyfluoroalcoholates. The polyfluoroenolates are, or will be useful as intermediate materials for synthesizing various organic fluoro-compounds.
In organic synthetic chemistry, the chemistry of enolates is an important field having wide applications. However, polyfluoroenolates have hitherto received but scant attention in both preparation and applications thereof.
It is known that lithium pentafluoro-2-propenolate is obtained by reacting pentafluoro-2-propenol with, for example, butyl lithium at a low temperature such as -78.degree. C. (Zh. Org. Khim., 12, 1379 (1976) ). Pentafluoro-2-propenol is a tautomer of pentafluoroacetone and, in laboratory, can be isolated in the enol form by distillation although the enol form is metastable state. Actually, however, it is difficult to obtain pentafluoro-2-propenol directly from pentafluoroacetone because aldol condensation of the isolated enol soon takes place. Therefore, it was devised to obtain pentafluoro-2-propenol by thermal decomposition or acid decomposition of a pentafluoro-2-propenyldialkyl-phosphate which is prepared by the Perkov reaction of chloropentafluoroacetone with a dialkyl- or trialkyl-phosphate (Zh. Org. Khim., 11, 1370(1975) ). However, by this process the total yield of the propenol is only 30-40%, and the high toxicity of chloropentafluoroacetone offers a serious problem to practical operations. Analogous difficulties are involved also in the preparation of other polyfluoroenols or polyfluoroenolates.